For example, I am looking at tickets in a week using created >= 2018-11-25 AND created <= "2018-12-01 23:59" , and at the same time I want to see how many of those were resolved within 7 days; meaning a ticket created on 11/25 should have a resolution date >= 2018-12-02 and ticket created on 2018-12-01 will have until 2018-12-08.
But if I use (created >= 2018-11-25 AND created <= "2018-12-01 23:59") and (resolutiondate >= 2018-11-25 AND resolutiondate <= "2018-12-08 23:59") that will cause tickets that are created on 2018-11-25 and resolved on 2018-12-07 to show up as well.